A common cause of premature compressor failure is excessive migration of refrigerant vapor to the crankcase of the compressor during the off cycle. When this happens, refrigerant vapor can condense back into a liquid, mix with the oil, and dilute its lubricating properties. On start-up, the oil/liquid refrigerant mixture is then used to lubricate the bearing surfaces within the compressor. This mixture — being a poor lubricant — causes wearing of the bearing surfaces within the compressor.
